A systematic literature search for studies reporting effects of Early Intensive Behavioral Intervention identified 34 studies, 9 of which were controlled designs having either a comparison or a control group. We completed a meta-analysis yielding a standardized mean difference effect size for two available outcome measures: change in full-scale intelligence and/or adaptive behavior composite. Effect sizes were computed using Hedges's g. The average effect size was 1.10 for change in full-scale intelligence (95% confidence interval = .87, 1.34) and .66 (95% confidence interval = .41, .90) for change in adaptive behavior composite. These effect sizes are generally considered to be large and moderate, respectively. Our results support the clinical implication that at present, and in the absence of other interventions with established efficacy, Early Intensive Behavioral Intervention should be an intervention of choice for children with autism.

An intervention group (n ϭ 23) of preschool children with autism was identified on the basis of parent preference for early intensive behavioral intervention and a comparison group (n ϭ 21) identified as receiving treatment as usual. Prospective assessment was undertaken before treatment, after 1 year of treatment, and again after 2 years. Groups did not differ on assessments at baseline but after 2 years, robust differences favoring intensive behavioral intervention were observed on measures of intelligence, language, daily living skills, positive social behavior, and a statistical measure of best outcome for individual children. Measures of parental well-being, obtained at the same three time points, produced no evidence that behavioral intervention created increased problems for either mothers or fathers of children receiving it.

This study was designed to evaluate 1 year of intensive treatment for 4- to 7-year-old children with autism. An independent clinician assigned children to either behavioral treatment (n = 13) or eclectic treatment (n = 12). Assignment was based on availability of personnel to supervise treatment and was not influenced by child characteristics or family preference. The two treatment groups received similar amounts of treatment (M = 28.52 hours per week at the child's school). Children in the behavioral treatment group made significantly larger gains on standardized tests than did children in the eclectic treatment group. Results suggest that some 4- to 7-year-olds may make large gains with intensive behavioral treatment, that such treatment can be successfully implemented in school settings, and that specific aspects of behavioral treatment (not just its intensity) may account for favorable outcomes.

This study extends findings on the effects of intensive applied behavior analytic treatment for children with autism who began treatment at a mean age of 5.5 years. The behavioral treatment group (n = 13, 8 boys) was compared to an eclectic treatment group (n = 12, 11 boys). Assignment to groups was made independently based on the availability of qualified supervisors. Both behavioral and eclectic treatment took place in public kindergartens and elementary schools for typically developing children. At a mean age of 8 years, 2 months, the behavioral treatment group showed larger increases in IQ and adaptive functioning than did the eclectic group. The behavioral treatment group also displayed fewer aberrant behaviors and social problems at follow-up. Results suggest that behavioral treatment was effective for children with autism in the study.

We evaluated outcomes for 31 children with autism (2–6 years of age at intake) who received behavioral intervention in mainstream pre-school settings and a comparison group of 12 children receiving treatment as usual. After 2 years, children receiving behavioral intervention had higher IQ scores (Hedges g = 1.03 (95% CI = .34, 1.72) and adaptive behavior composite scores (Hedges g = .73 (95% CI = .05, 1.36). Despite probably fewer intervention hours, these group level outcomes were comparable to studies providing more intensive intervention. Individual child data also showed positive results with 19.4% achieving change at a reliable level for IQ; but a lower percentage than found in recent meta-analysis research. Strengths and weaknesses of the mainstream pre-school delivery model are discussed.